You are right, until a quantum entity such as an electron or proton is observed it exists only within a probability wave. But once it is observed the probability wave aspect of its reality collapses and the entity becomes a particle.
“You are right, until a quantum entity such as an electron or proton is observed it exists only within a probability wave.”
Well, that’s one interpretation. The math works well to view the waves as “probability waves” but it doesn’t make much sense empirically. It makes more sense if the waves are just actual waves, and the “probability” is simply something inherent to the nature of matter being in a wave state.